Electroluminescence Characteristics of Epoxy/TiO2 Nanocomposites

The AC breakdown strength of epoxy/TiO2 nanocomposites (NC) with agglomerate sizes smaller than 50 nm is higher than that of unfilled epoxy. However, the mechanism responsible for this breakdown strength enhancement has not been clarified. Observing the electroluminescence (EL) of these materials may provide insight into insulation deterioration in the early stages. This study investigated the EL characteristics of unfilled epoxy and NC to clarify the mechanism for the enhancement of the breakdown strength. We fabricated NCs with controlled agglomerate sizes using centrifugation. The EL of NC was measured under an AC ramp electric field. The number of EL pulses of the NC is found to be less than that of the unfilled epoxy. The EL inception and extinction electric fields of the NC are higher than those of the unfilled epoxy. These results indicate that the dispersed nanoparticles suppress EL generation.

I. Introduction

Epoxy resins are utilized as solid insulating materials in power apparatus [1]. Enhancement of the breakdown strength of the epoxy resin optimizes the insulation design of the apparatus, which can help realize highly efficient generators and compact switchgears. Recently, it has been reported that nanofiller addition to epoxy resin can enhance its breakdown strength [2]. The nanofiller effect depends on several factors, including the nanofiller material, particle size [3], filler volume fraction [4], interface state [5], and particle dispersion [6]. To optimize the manufacturing process of epoxy nanocomposites (NCs), it is important to clarify the mechanism that enhances the breakdown strength of the NCs.